<FIRST DRAFT, based on a Forum post by fehlix>
A linux user-account is kind of / or similar to a Swiss bank account: it has a account “name” and a account-“number/id”.
Those two properties are bound to the account. The user-name is meant for
visual identification of the account, e.g when you login you’d rather prefer to
select/enter the user “name”. And also the “home” folder name defaults to the
user-account “name”. Now anything related to access/change permission of the possession of that account, similar to a Swiss bank account, requires/or is controlled by the account-number id.
In MX Linux when you create the first user-account, you are free to give this user a name.
The first user-id starts with number 1000. If you create a 2nd user (account),
you can choose the name but the id would be the next free available, which is 1001.
You can see the ownership of you file by running in the terminal
The ownship and group-membership is listed as a number both start with 1000,
for the first user.
For convieniece the user-id/group-id is normally “translated” on the fly
to the correspinding user-name and group-name, e.g. when you run
or also shown within Thunar, when added to display ownership.
But remember: the access permission is controlled by the id/number of
the owner and the group membership, not by the translated names.